Redox flow battery system for distributed energy storage

Abstract

A large stack redox flow battery system provides a solution to the energy storage challenge of many types of renewable energy systems. Independent reaction cells arranged in a cascade configuration are configured according to state of charge conditions expected in each cell. The large stack redox flow battery system can support multi-megawatt implementations suitable for use with power grid applications. Thermal integration with energy generating systems, such as fuel cell, wind and solar systems, further maximize total energy efficiency. The redox flow battery system can also be scaled down to smaller applications, such as a gravity feed system suitable for small and remote site applications.

We claim: 
     
       1. An electrical power system, comprising:
 a source of electrical power; and 
 a redox flow battery system coupled to the source of electrical power, and configured to receive electrical power from the source of electrical power and provide electrical power to an electrical load, the redox flow battery system comprising:
 a first tank for storing a catholyte reactant; 
 a second tank for storing an anolyte reactant; and 
 a first redox flow battery stack assembly coupled to the first tank and the second tank, the first redox battery stack assembly comprising:
 a first plurality of cells arranged along a first reactant flow path, the first reactant flow path having a first end and a second end, wherein an outlet of a first one of the first plurality of cells is coupled to an inlet of a second one of the first plurality of cells, the first one of the first plurality of cells having a first at least one of: a structural configuration and a material configuration, according to a first position along the first reactant flow path, the second one of the first plurality of cells having a second at least one of: a structural configuration and a material configuration, according to a second position of the second one of the first plurality of cells along the first reactant flow path, wherein the first at least one and the second at least one of: the structural configuration and the material configuration are different based on the first position and the second position along the reactant flow path so as to improve a total energy efficiency of the redox flow battery system. 
 
 
 
     
     
       2. The electrical power system of  claim 1 , wherein:
 the redox flow battery system further comprises a second redox flow battery stack assembly coupled to the first tank and the second tank, the first redox battery stack assembly, the second redox flow battery stack assembly comprising a second plurality of cells arranged along a second reactant flow path, the second reactant flow path having a first end and a second end, wherein an outlet of a first one of the second plurality of cells is coupled to an inlet of a second one of the second plurality of cells the first one of the second plurality of cells having a first at least one of: a structural configuration and a material configuration, according to a first position along the second reactant flow path, the second one of the second plurality of cells having a second at least one of: a structural configuration and a material configuration, according to a second position of the second one of the second plurality of cells along the second reactant flow path the first at least one and the second at least one of: the structural configuration and the material configuration improving a total energy efficiency of the redox flow battery system; 
 the first redox flow battery stack assembly is connected to the source of electrical power and is configured to charge catholyte and anolyte reactants; and 
 the second redox flow battery stack assembly is connected to the electrical load and is configured to discharge catholyte and anolyte to provide electrical power to the electrical load. 
 
     
     
       3. The electrical power system of  claim 2 , wherein the source of electrical power is selected from a solar array, a wind turbine, a fuel cell, a nuclear power plant, a coal-fired power plant, an intermittent power source, and a base-loaded power source. 
     
     
       4. The electrical power system of  claim 1 , wherein at least one component of the first one of the first plurality of cells and the second one of the first plurality of cells has at least one of: a structural configuration and a material configuration according to a respective state of charge range of electrolytes in the at least one of the first one of the plurality of cells and the second one of the plurality of cells along the first reactant flow path, wherein the respective state of charge range is based on charge states in cells during operation of the electrical power system, wherein the at least one component is selected from a separator membrane, a porous electrode, an electrode catalyst, and an electrode chamber. 
     
     
       5. The electrical power system of  claim 1 , further comprising a heat exchanger, wherein the source of electrical power comprises a cooling system that outputs hot fluid and the heat exchanger is configured to use hot fluid from the electrical power source cooling system to heat reactant flowing through the first redox flow battery stack to a range of about 40° C. to about 65° C. 
     
     
       6. The electrical power system of  claim 1 , further comprising a heat exchanger, wherein the electrical load comprises a cooling system that outputs hot fluid and the heat exchanger is configured to use hot fluid from the load cooling system to heat reactant stored in the tanks to about 40 to 65° C. 
     
     
       7. The electrical power system of  claim 1 , further comprising:
 a source of geothermal energy that outputs a hot fluid; and 
 a heat exchanger, 
 wherein the heat exchanger is configured to use hot fluid from the geothermal system to heat reactant to a range of about 40° C. to about 65° C. 
 
     
     
       8. The electrical power system of  claim 7 , wherein the source of electrical power comprises one of a wind turbine, a solar energy conversion system, and a fuel cell. 
     
     
       9. The electrical power system of  claim 1 , wherein the electrical load comprises one of an electric vehicle charging system, a data center, a manufacturing center, an industrial facility and an inverter electrically coupled to a utility grid. 
     
     
       10. An electrical power system, comprising:
 a source of electrical power; and 
 a redox flow battery system configured to receive electrical power from the source of electrical power and provide electrical power to an electrical load, the redox flow battery system comprising:
 a first tank for storing a catholyte reactant comprising a first tank separator configured to inhibit mixing of charged catholyte reactant with discharged catholyte reactant; 
 a second tank for storing an anolyte reactant comprising a second tank separator configured to inhibit mixing of charged anolyte reactant with discharged anolyte reactant; and 
 a redox flow battery stack assembly comprising a plurality of cells arranged along a reactant flow path, the flow path having a first end and a second end, wherein the plurality of cells are configured according to their position along the reactant flow path. 
 
 
     
     
       11. The electrical power system of  claim 10 , wherein each of the first and second tank separators is positioned vertically and wherein each tank and its respective tank separator are configured so that the tank separator moves as reactant is pumped into each tank on one side of the tank separator and is drawn out of each tank from the other side of the tank separator so that mixing of charged reactant with discharged reactant is inhibited. 
     
     
       12. The electrical power system of  claim 1 , further comprising:
 a third tank for storing discharged catholyte reactant; and 
 a fourth tank for storing discharged anolyte reactant, 
 wherein the system is configured to flow charged catholyte from the first tank through the first redox flow battery stack assembly and into the third tank and flow charged anolyte from the second tank through the first redox flow battery stack assembly and into the fourth tank while operating in discharge mode. 
 
     
     
       13. The electrical power system of  claim 1 , further comprising:
 a third tank for storing discharged catholyte and anolyte reactants, 
 wherein the system is configured to flow charged catholyte from the first tank through the first redox flow battery stack assembly and into the third tank and flow charged anolyte from the second tank through the first redox flow battery stack assembly and into the third tank while operating in discharge mode, and to flow electrolytes from the third tank through the first redox flow battery stack assembly and into each of the first and second tanks while operating in charge mode. 
 
     
     
       14. The electrical power system of  claim 1 , wherein the redox flow battery system is configured to operate with the catholyte reactant and the anolyte reactant flowing in the same direction in both charge mode and discharge mode. 
     
     
       15. The electrical power system of  claim 1 , wherein the first redox flow battery stack assembly is configured to charge the catholyte and anolyte reactants when the reactants are flowing in a first direction away from the first end towards the second end and to discharge the catholyte and anolyte reacts when the reactants are flowing in a second direction away from the second end towards the first end. 
     
     
       16. An electrical power system, comprising:
 a source of electrical power; and 
 a redox flow battery system coupled to and configured to receive electrical power from the source of electrical power and provide electrical power to an electrical load, the redox flow battery system comprising: 
 a first tank for storing a catholyte reactant; 
 a second tank for storing an anolyte reactant; and 
 a first redox flow battery stack assembly coupled to the first tank and the second tank, the first redox battery stack assembly comprising an array of cells arranged to form catholyte and anolyte reactant flow paths, wherein the array of cells is configured so that catholyte and anolyte reactants flow from a first cell to a last cell in a cascade orientation, and wherein an outlet of a first cell in the array of cells is coupled to an inlet of a second cell in the array of cells, wherein the first cell comprises at least one component having at least one of: a structural configuration and a material configuration to improve total energy efficiency of the redox flow battery system the at least one of: the structural configuration and the material configuration based on a state-of-charge range of reactants in the first cell along the catholyte and anolyte reactant flow paths, wherein the at least one of: the structural configuration and the material configuration of the at least one component of the first cell is different from at least one of: a structural configuration and a material configuration of others of the array of cells. 
 
     
     
       17. The electrical power system of  claim 16 , further comprising an electrical load electrically coupled to the first redox flow battery stack assembly, the electrical load comprising at least one of an electric vehicle charging system, a data center, a manufacturing center and an inverter electrically coupled to a utility grid. 
     
     
       18. The electrical power system of  claim 17 , wherein the source of electrical power comprises one or more of a fuel cell, a solar energy conversion system, a wind turbine, a geothermal energy system, and an inverter coupled to a utility grid. 
     
     
       19. The electrical power system of  claim 10 , wherein each of the first and second tank separators is buoyant, includes a valve mechanism which when opened allows reactant to flow through the tank separator, and is configured so that when the valve mechanism is closed mixing of charged reactant with discharged reactant is inhibited and when the valve mechanism is opened the tank separator will float to a top surface of the reactant.